Collapsible vehicle-steering systems

ABSTRACT

An improved collapsible vehicle-steering system comprising a steering wheel and steering wheel shaft assembly extending between the steering wheel and means for transmitting steering wheel movement to the vehicle wheels. The shaft assembly is divided into an upper section and a lower section arranged for coaxial movement relative to each other. The upper shaft section carries the steering wheel and is freely movable axially from a first steering position to a second safe position and is releasably held in its first steering position by a latch means which co-acts with means sensitive to vehicle retardation forces. The means sensitive to vehicle retardation forces is adapted to actuate the upper shaft section latching means at forces exceeding a predetermined magnitude, to permit axial movement of the upper shaft section relative the lower, from said first position to said second position.

United, States Patent [191 Bane [ COLLAPSIBLE VEHICLE-STEERING SYSTEMS[7 5] Inventor:

[73] Assignee: AB Volvo, Goteborg, Sweden [22] Filed: Nov. 6, 1972 211App]. No.: 303,946

Lars Olof Bane, Goteborg, Sweden [52] US. Cl. 74/492, 74/2 [51] Int. ClB62d 1/18, G05g 17/00 [58] Fieldof Search 74/492, 493; 280/150 B [56] LReferences Cited UNITED STATES PATENTS l/l970 Fergle.,., ..74/49215/1964 Zazzara....

3,397,911 8/1968 Brosius..... 280/150 B 3,483,768 12/1969 Glass 74/4923,699,824 10/1972 Standenmayer 74/492 FOREIGN PATENTS OR APPLICATIONS739,676 11/1955 Great Britain 280/150 B [4 Feb. 12, 1974 PrimaryExaminerAIlan D. Hermann Attorney, Agent, or FirmYoung & Thompson [5 7]ABSTRACT An improved collapsible vehicle-steering system comprising asteering wheel and steering wheel shaft assembly extending between thesteering wheel and means for transmitting steering wheel movement to thevehicle wheels. The shaft assembly is divided into an upper section anda lower section arranged for coaxial movement relative to each other.The upper shaft section carries the steering wheel and is freely movableaxially from a first steering position to a second safe position and isreleasabl y held in its first steering position by a latch means whichco-acts with means sensitive to vehicle retardation forces. The

means sensitive to vehicle retardation forces is adapted to actuate theupper shaft section latching means at forces exceeding a predeterminedmagnitude, to permit axial movement of the upper shaft section relativethe lower, from said first position to said second position.

12 Claims, 2 Drawing Figures t COLLAPSIBLE VEHICLE-STEERING SYSTEMS Thepresent invention relates to an improvement in collapsiblevehicle-steering systems of the type comprising a steering wheel and asteering shaft assembly extending between the steering wheel andmovement transmission means for transmitting rotary movement of thesteering wheel and the steering shaft assembly to the vehicle wheels,and with which systems the steering shaft assembly is divided into anupper, steering wheel carrying shaft section and a lower steering shaftsection arranged for axial movement relative to each other, so that whensubjected to impact forces acting generally in the direction of theirrespective longitudinal axis the shaft sections are able to move axiallyin a manner to reduce the effect of the impact on the driver of thevehicle.

Serious efforts are being made in the automobile industries to reducethe extent of injuries sustained through automobile collisions, byintroducing for example as standard automobile equipment such safetydevices as safety belts, self-inflating impact cushions, recedingdriving instruments, off-line engine installations and collapsiblesteering systems etc. The present invention relates to this latter typeof safety device. Collapsible steering systems are known to the art withwhich the steering shaft is divided into an upper steering shaftsection, which carries the steering wheel of the vehicle and a lowersteering shaft section, and with which the sections are drivinglyconnected together and arranged to move axially in relation to eachother when subjected to heavy impact forces acting substantially in thedirection of their longitudinal axis, so that in the event of acollision between two vehicles for example, the lower steering shaftsection is able to yield against externally acting forces, such as theimpact force on the front portion of the vehicle.

With one such known collapsible steering system, the upper shaft sectioncarrying the steering wheel is axially offset relative the lower shaftsection, so that forces acting axially on the lower section cause thesame to move parallel to the upper section, whereby the lower shaftsection, if acted upon by frontal impact forces of sufficient magnitudeis moved upwards outside the line of the driver, while the upper,steering wheel carrying shaft section is forced downwards by the forceexerted on the steering wheel by'the body of the driver as he is thrownforwards.

One common feature with such collapsible vehiclesteering systems,however, is that only the lower steering shaft section is able to moveaxially while the upper shaft section is held rigid. While such anarrangement might possibly alleviate injury to the driver of a vehicleas the result of steering wheel impact, it is obvious that personalinjury will nevertheless be' sustained at the moment of impact betweenthe driver and the steering wheel.

The main object of the invention is to eliminate this hazard and it isproposed in accordance therewith to provide a collapsible vehiclesteering system which comprises a steering wheel and a steering shaftassem bly extendingbetween the steering wheel and movement transmissionmeans for transmitting rotary movement of the steering wheel and thesteering shaft assembly to the vehicle wheels, wherein the steering,shaft as sembly comprises upper andlower shaft sections arranged foraxial movement relative to each other, of

which sections the upper section is attached to the steering wheel andarranged for free axial movement froma first, steering position to asecond, safe steering position located at least generally remote fromthe vicinity of possible steering wheel contact with the driver, andfurther comprising latching means for releaseably holding the uppersteering shaft section in said first position, and means sensitive tovehicle retardation forces for releasing said latching means when saidvehicle retardation forces exceed a predetermined magnitude, to permitfree movement of the upper shaft section to said second, safe position.In this way, it is ensured that minimum injurious bodily contact takesplace between the driver of the vehicle and the steering wheel, but thatwhen the vehicle is subjected to frontal impact forces the steeringwheel freely moves away from the first steering position to said safeposition, substantially out of reach of the body of the driver.

According to one feature of the invention, the upper steering shaftsection carrying the steering wheel is capable of moving to the second,safe position under its own weight and that of the steering wheel orunder the influence of the mass forces acting on said shaft section andsaid steering wheel. In certain instances, however, it may be foundexpedient to provide auxiliary means to ensure rapid and positivemovement of the upper steering shaft section tothe second, safeposition. Accordingly, with one alternative feature of the inventionthere is arranged a spring which biasses the upper steering shaftsection towards the second, safe position. I

Further, to prevent possible rebound of the freely movable. uppersteering shaft section from the second, safe position back towards thenormal vehicle steering position it is suitable in certain instances toprovide means which prevent movement of the upper steering shaft sectiontowards its normal vehicle steering, once it has moved towards the safeposition,

These and other important features of the invention will be apparentfrom the following description which is given with reference to twoembodiments thereof illustrated in the accompanying drawings, in whichFIGS. 1 and 2 illustrate diagrammatically part of the drivingcompartment of a motor vehicle steering system incorporating theprincipal of the invention.

Illustrated in FIG. 1 of the drawings is a driving seat 10, aninstrument panel, 11 having disposed therein a recess 12 shaped toaccommodate the steering wheel of the vehicle as hereinafter described,and a windscreen l3 of conventional design, forming part of aconventional motor vehicle. Also shown in FIG. 1 is part of avehicle-steering system 14, comprising an upper steering shaft section15 attached to a steering wheel 16, and a lower steering shaft section17 attached to means for transmitting the rotary movement of thesteering wheel and the steering shaft to the tie rods of the vehicle.Since the movement transmission means is not concerned with the conceptof the present invention it will not be illustrated or described inconnection therewith, with the exception of a universal joint 18 shownconnected to the bottom of the lower steering shaft section 17 andcooperating with the remainder of the movement transmission means notshown.

In the exemplary embodiments, the upper steering shaft section 15 is ofhollow splined construction and is arranged coaxially with the lowersplined shaft section 17 for telescopic movement relative thereto. Axialmovement of the shaft section 15 relative the shaft section 17 from theillustrated normal vehicle steering position, in which the steeringwheel 16 occupies a steering position remote from the instrument panel11, to a safe position (not shown), in which the steering wheel isaccommodated in the recess 12 generally out of the vicinity of possiblecontact with the driver, is prevented by latching means, which in thefirst embodiment comprises a latching element 19, pivotally hinged asindicated at 20 to a bracket structure 21 mounted to a suitable part ofthe vehicle and a toggle link arrangement 22 co-acting with the latchingelement 19. It should be mentioned that the splined engagement of theupper and lower steering shaft sections is such that the steering wheelcan still be used to steer the vehicle when occupying the second safeposition. In the first embodiment, the latching element is of triangularconfiguration. Obviously, the latching element could equally as well beL-shaped, with one surface serving as the active latching component andthe other as the component co-acting with the toggle link 19.

The toggle link arrangement has two positions, i.e. a first stableposition in which the latching element 19 is held in latching engagementto prevent axial movement of the upper steering shaft section to thesafe position at mass forces below a certain predetermined magnitude,and a second position in which the latching element is released andallowed to swing counterclockwise from its latching position to aposition in which the upper steering shaft section and the steeringwheel 16 are free to move to the safe position, the steering wheel 16being received in the recess 12 substantially out of range of thelunging body of the driver of the vehicle.

In the first position of the toggle link arrangement, in which thelatching member 19 is held in its operative position, the centre pivotpoint 23 is preferably located to the right as seen in FIG. 1 of animaginary line passing through the point 24 at which the lower link 25of the toggle link is anchored to the vehicle and the point 26 at whichthe upper link 27 of the toggle link contacts the latching element 19.Thus, in order to release the latching element, to permit axial movementof the upper steering shaft section 15 towards the safe position thecentre pivot point 23 must be moved across the aforementioned imaginaryline, to a position on the left thereof, i.e. to the second position ofthe toggle link arrangement 22. Accordingly, there is arranged a latchrelease means, which is the first embodiment has the form of a weight 28arranged to co-act with the toggle link arrangement 22 in a manner tomove the same from its first position to its second position by theinertia forces acting on the weight as the result of vehicle retardationforces exceeding a certain predetermined magnitude. Thus, in the eventof a collision, the toggle link is subjected to mass forces exerted bythe weight 28 which in the first embodiment is attached to the lowerlink 25 of the toggle link arrangement 22, and is moved to the secondposition, thereby releasing the latching element 19 and permitting thesteering wheel 16 and the upper steering shaft section 15 to move to thesecond position as a result of the mass forces acting thereon.

As will be readily perceived, the angle subtended by the links 25,27 atthe centre pivot point 23 of the toggle link arrangement 22 should besuch as to prevent movement of the arrangement to its second positionupon the occurance of minor impact forces, thereby preventingunnecessary release of the latching element 19. At the same time,however, this angle should not be so great as to prevent rapid movementof the toggle link arrangement to the second position when impact forcesof a dangerous magnitude are experienced. In other words the anglesubtended by the links 25, 27 of the toggle link arrangement adjacentthe central pivot point 23, and the weight 28 should be adapted to causerapid movement of the toggle link arrangement 22 to its second positionwith impact forces exceeding a predetermined magnitude, and to allow thetoggle link arrangement 22 to remain in its first position with impactforces below this magnitude. The positioning of the weight 28 relativethe toggle link arrangement 22 and the actual construction andorientation of the toggle link arrangement itself, however, are mattersof design choice, the important thing being that the combinedarrangement of the toggle link and weight cause practicallyinstantaneous release of the latching element 19 at the very moment ofimpact. Thus, for example, the lower link 25 of the toggle linkarrangement 22 can be supported against rearward movement by stationarystop means 29 mounted behind and adjacent to the lower link attachmentmeans. Alternatively the adjacent ends of links 25 and 27 may beconstructed in a manner not shown to prevent unsuitable position of thecentre point 23 to the right of the imaginary line passing through thecontact point 26 and the attachment point 24.

In certain instances means may be provided to assist the mass forcesmoving the upper steering shaft section 15, and thus also the steeringwheel 16, to the safe position immediately the latching member 19 isreleased by the latch release means, thereby ensuring positive and rapidmovement of the steering wheel 16 into the recess 12.

In both embodiments, the latching element 19 acts on the upper steeringshaft section 15 via a sleeve 30 which extends over the section 15 andis arranged for axial movement therewith but is locked against rotationaround its own longitudinal axis. As will be seen from the drawings, theupper steering shaft section 15 is journalled in the sleeve 30 in abearing 31, and the sleeve 30 has fixedly mounted at the end thereofremote from the bearing 31 an abutment 32, against one surface of whichthe latching element 19 is arranged to bear when occupying its latchingposition.

As previously mentioned, if desired, axial movement of the steeringwheel 16 and the upper steering shaft section 15 may be assisted byspring means. Accordingly, both illustrated embodiments include a coilspring 33 acting between a substantially immovable abutment surfacearranged externally of the sleeve 30 and the free surface of theabutment 32 located on the sleeve 30. Thus, when the latching element 19is released from its latching position by the toggle link arrangement 22in the aforedescribed manner, the force exerted by the spring 33 on thesleeve 30 via the abutment 32 assists the mass forces acting on theupper steering shaft section 15 and the steering wheel to move the sameto the safe position.

In both embodiments, the abutment surface arranged externally of thesleeve 30 and serving as one thrust surface for the spring 33 has theform of an annular shoulder 34 mounted to a further sleeve 35. Thesleeve 35 extends .over a substantial length of the sleeve 30 and isprovided with a bearing means 36 attached to the sleeve 35 by screws orthe like and permitting rotary movement of the lower steering shaftsection 17. The sleeve 35 is fixed against axial movement by appropriatemeans not shown and is provided with an opening 37 to permit movement ofthe latching element into and out of engagement with the abutment 32.

As previously indicated, to safeguard against possible rebound of theupper steering shaft section 15, and thus also the steering wheel 16,from the safe position towards the normal steering position once thelatching means is released, there may be provided in accordance with theinvention a device which while permitting axial movement of the uppershaft section towards the safe position effectively prevents movement ofthe upper shaft section in the reverse direction. A suitable device forthis purpose is shown in the drawings and, for example, comprises asegmented or yielding frusto-conical insert 38 loosely inserted betweenthe non-movable annular abutment 34 and the sleeve 30. As will be seenfrom the drawings, the inner surfaces of the abutment 34 conform withthe outer surfaces of the insert 38, so that while the sleeve is able tomove axially downwards towards the safe position, as a result of slightfriction forces acting between the insert 38 and the sleeve 30, anymovement of the sleeve 30 towards the normal steering position willcause deformation of the insert against the sleeve, thereby effectivelywedging the same against continued movement. a

In the second embodiment, shown in FIG. 2, the means latching the uppershaft section 15 against axial movement towards the safe positioncomprises a latching element, in the form of a pin or stud 40 forexample, which carries an explosive charge 41 and which, in response toa signal transmitted by an electronic device 43, 44, 45 sensitive at 46to vehicle retardation forces of a predetermined magnitude and locatedin the front portion 42 of the vehicle for instance, is caused toexplode and disintegrate, thereby releasing the upper steering shaftsection 15 and the steering wheel 16 attached thereto for immediatemovement to the safe position as a result of the mass forces actingthereon.

Although the latching means of theillustrated embodiments acts on theupper steering shaft section via the sleeve 30, it also lies within thepurview of the invention to'cause the latching means to act directly onthe upper steering shaft section 15. For example, it is conceivable thatthe upper steering shaft section 15 is provided with a circumferentiallyextending collar and that the latching element has the form of aspringloaded roller, for example, engaging the under surface of theannular collar to prevent downward axial movement of said shaft section.Neither is the improvement of the present invention solely applicable tosplit steering shaft assemblies with which the upper and lower shaftsections are coaxial, but can be applied equally as well to shaftassemblies with which the shaft sections are offset in relation to eachother.

What is claimed is:

l. A collapsible steering wheel system comprising a steering wheel and asteering shaft assembly extending between the steering wheel andmovement transmissionmeans for transmitting rotary movement of thesteering wheel and the steering shaft assembly to the vehicle wheels,the steering shaft'assembly comprising upper and lower shaft sections,said upper. section beingattached tothe steering wheel, means mountingsaid upper section for free axial movement relative to said lower shaftsection from a first upper steering position to a second lower safeposition, latching means releasably holding the upper shaft section insaid first position, and means responsive to vehicle retardation forcesfor releasing said latching means when said retardation forces exceed apredetermined magnitude thereby to permit free movement of said uppershaft section to said second position.

2. A collapsible vehicle-steering system according to claim 1, whereinthe upper and lower shaft sections are co-axial and arranged fortelescopic movement in relation to each other.

3. A collapsible vehicle-steering system according to claim 1, whereinthe upper steering shaft section is movable to said second safe positionunder its own weight and the weight of the steering wheel attachedthereto.

4. A collapsible vehicle-steering system according to claim 1, whereinsaid upper steering shaft section is spring biassed towards said second,safe position.

5. A collapsible vehicle-steering system according to claim 1, whereinthe releaseable latching means includes a sleeve that acts on the uppersteering shaft section, said sleeve extending over said section andbeing arranged for axial movement therewith but being locked againstrotation about its own longitudinal axis.

6. A collapsible vehicle-steering system according to claim 5, and aspring acting between a first abutment surface arranged externally ofthe sleeve and being immovable relative thereto, and a second abutmentsurface located on said sleeve to urge said upper section toward saidsecond position.

7. A collapsible vehicle-steering system according to claim 6, whereinsaid second abutment surface prevents return movement of the uppersteering shaft section from the second safe position towards the first,normal steering position.

8. A collapsible vehicle-steering system according to claim 1, whereinthe latch release means comprises a movable weight which, upon theoccurrence of vehicle retardation forces above a predeterminedmagnitude, as a result of the inertia forces acting thereon causes thelatching means to release the upper steering shaft section for movementof said section to said second, safe position.

9. A collapsible vehicle-steering system according to claim 1, whereinthe latching means comprises a latching element co-acting with a toggle.link arrangement which in a first position holds the latching element inits active latching position and in a second position releases saidlatching element from said latching position.

110. A collapsible vehicle-steering system according to claim 9, saidlatch release means comprising a movable weight connected to said togglelink arrangement in a manner to move said toggle link arrangement fromits first position to its second position by the inertia forces actingon the weight as the result of vehicle retardation forces above apredetermined magnitude.

11. A collapsible vehicle-steering system according to claim 9, whereinthe latching element has two edge surfaces extending to subtend an angletherebetween and is pivotally mounted to a fixed point on the vehicle,one of said edge surfaces being arranged to latch the upper steeringshaft section against movement from the being of hollow construction andarranged for telescopic movement with the other steering shaft section,said lower steering shaft section being encircled by an axiallyimmovable further sleeve extending over at least a considerable lengthof the first mentioned sleeve and embodying said first, spring abutmentsurface.

1. A collapsible steering wheel system comprising a steering wheel and asteering shaft assembly extending between the steering wheel andmovement transmission means for transmitting rotary movement of thesteering wheel and the steering shaft assembly to the vehicle wheels,the steering shaft assembly comprising upper and lower shaft sections,said upper section being attached to the steering wheel, means mountingsaid upper section for free axial movement relative to said lower shaftsection from a first upper steering position to a second lower safeposition, latching means releasably holding the upper shaft section insaid first position, and means responsive to vehicle retardation forcesfor releasing said latching means when said retardation forces exceed apredetermined magnitude thereby to permit free movement of said uppershaft section to said second position.
 2. A collapsible vehicle-steeringsystem according to claim 1, wherein the upper and lower shaft sectionsare co-axial and arranged for telescopic movement in relation to eachother.
 3. A collapsible vehicle-steering system according to claim 1,wherein the upper steering shaft section is movable to said second safeposition under its own weight and the weight of the steering wheelattached thereto.
 4. A collapsible vehicle-steering system according toclaim 1, wherein said upper steering shaft section is spring biassedtowards said second, safe position.
 5. A collapsible vehicle-steeringsystem according to claim 1, whErein the releaseable latching meansincludes a sleeve that acts on the upper steering shaft section, saidsleeve extending over said section and being arranged for axial movementtherewith but being locked against rotation about its own longitudinalaxis.
 6. A collapsible vehicle-steering system according to claim 5, anda spring acting between a first abutment surface arranged externally ofthe sleeve and being immovable relative thereto, and a second abutmentsurface located on said sleeve to urge said upper section toward saidsecond position.
 7. A collapsible vehicle-steering system according toclaim 6, wherein said second abutment surface prevents return movementof the upper steering shaft section from the second safe positiontowards the first, normal steering position.
 8. A collapsiblevehicle-steering system according to claim 1, wherein the latch releasemeans comprises a movable weight which, upon the occurrence of vehicleretardation forces above a predetermined magnitude, as a result of theinertia forces acting thereon causes the latching means to release theupper steering shaft section for movement of said section to saidsecond, safe position.
 9. A collapsible vehicle-steering systemaccording to claim 1, wherein the latching means comprises a latchingelement co-acting with a toggle link arrangement which in a firstposition holds the latching element in its active latching position andin a second position releases said latching element from said latchingposition.
 10. A collapsible vehicle-steering system according to claim9, said latch release means comprising a movable weight connected tosaid toggle link arrangement in a manner to move said toggle linkarrangement from its first position to its second position by theinertia forces acting on the weight as the result of vehicle retardationforces above a predetermined magnitude.
 11. A collapsiblevehicle-steering system according to claim 9, wherein the latchingelement has two edge surfaces extending to subtend an angle therebetweenand is pivotally mounted to a fixed point on the vehicle, one of saidedge surfaces being arranged to latch the upper steering shaft sectionagainst movement from the first normal steering position towards thesecond, safe position, and the other edge surface engaging the togglelink arrangement to retain the latching member in its operative,latching position.
 12. A collapsible vehicle-steering system accordingto claim 6, wherein the upper steering shaft section and the lower shaftsection are splined, one of said sections being of hollow constructionand arranged for telescopic movement with the other steering shaftsection, said lower steering shaft section being encircled by an axiallyimmovable further sleeve extending over at least a considerable lengthof the first mentioned sleeve and embodying said first, spring abutmentsurface.